docs: def _check_equals(self):
          """
          check for = in position 8, set attribute _has_equals
          """
          card_string = self['card_string']
          if len(card_string) < 9:
              self._has_equals = False
          elif card_string[8] == '=':
              self._has_equals = True
          else:
              self._has_equals = False